Genetic engineering of chloroplast genome using a large-chloroplast mutant in rice

高等植物叶绿体基因组的基因工程自1980年S以来一直在尝试，并在烟草和几个物种上取得了成功。与核基因组相比，叶绿体转化具有优势，因为基因组的母性遗传消除了转基因通过花粉的传播，ii)没有基因沉默使转基因能够高水平表达，iii)同源重组将转基因定位于所需的基因组区域。尽管有这些优势，但水稻和其他作物的叶绿体转化效率极低。我们推测，其中一个障碍可能是这些物种的叶绿体体积较小。在这项研究中，我们建议利用一个叶绿体变大的突变体。分离和鉴定了一个水稻叶绿体大突变体，鉴定了导致该突变的基因，并尝试利用该突变体进行水稻叶绿体转化。

Genetic engineering of chloroplast genome in higher plants has been attempted since 1980’s, and has been successful in tobacco and several species. Chloroplast transformation has advantages over nucleargenome, because i) maternal inheritance of the genome eliminates dispersal of a transgene through pollen, ii) no gene silencing allows transgene to be expressed at highlevel, and iii) homologous recombination targets a transgene into a desired genomic region. Despite such advantages, efficiency of chloroplast transformation is extremely low in rice and other crops. We reasoned that one obstacle may be a small size of chloroplasts in these species. In this study, we propose to utilize a mutant that has enlarged chloroplasts. Isolation and characterization of a rice mutant showing large chloroplasts, identification of the gene responsible for this mutation, and an attempt to use this line for rice chloroplast transformation, have been conducted.